The present invention relates to methods and systems for communicating data in a monitoring system such as a vehicle security system.
In a vehicle messaging system, such as an emergency messaging system or a vehicle security system, a central station contacts a subscriber telephone in a vehicle to download and/or upload data associated with the vehicle. The data can include vehicle tracking data and/or theft reporting data, or other data pertinent to the vehicle or its operator.
At times, the central station may need to contact the subscriber telephone when the vehicle is unpowered. To be prepared to receive a data download call from the central station, the subscriber telephone can be continually powered by a battery of the vehicle. A shortcoming of this approach is that the subscriber telephone drains energy from the battery for a potentially long duration of time (e.g. many hours) while the vehicle is unpowered. Hence, a potentially significant amount of energy may be drained from the battery using this approach, which makes it impractical.
Another known approach is to have the subscriber telephone powered-on responsive to a vehicle door handle. An electrical contact can be sensitive to use of a driver-side door handle, for example, to recognize an open vehicle door. The subscriber telephone is powered-on in response to the electrical contact. This approach requires a driver, or vehicle operator, to be present which can be impractical.
A further known approach is to have the subscriber telephone powered-on responsive to a pager device in the vehicle. The central station initiates a paging message to the pager when a data download call is to occur. The subscriber telephone is powered-on in response to the pager receiving the paging message. Thereafter, the subscriber telephone automatically answers an ensuing incoming call from the central station. After communicating data to the central station in the call, the subscriber telephone is returned to an unpowered state.
A shortcoming of any known automatic answering scheme is that the subscriber telephone can automatically answer a non-download call. For example, a caller (e.g. another person) may initiate a call to a driver or a passenger of the vehicle which is automatically answered by the subscriber telephone. By automatically answering the call, the caller and/or the subscriber may be charged for the call even though neither the driver nor the passenger is present to answer.
Another shortcoming is that if the driver is present in the vehicle when a data call comes in, the driver or a passenger may pick up a handset of the subscriber telephone. This action can interrupt the data call, and can generate an associated charge to the subscriber.
What is needed is an improved approach to handling voice and data calls in a vehicular emergency messaging system, both when an operator is present and when an operator is absent, including optimum energy preservation and prevention of improper automatic answering.